A bicycle chain is a complex structure that incorporates different mechanisms with specific and often contradictory lubrication requirements.
In the first place, a bicycle chain operates in a very dusty environment. Accordingly, its lubricant should be non-tacky, that is dry or of a low viscosity. This requirement would normally exclude greases in favor of solid lubricants. Indeed, any mineral dust collected by a tacky lubricant will eventually cause abrasion and rapid wear of bearing surfaces. The low pressure, low velocity and limited intermittent frictional movement between the lateral link plates of the chain can be adequately lubricated with a solid or thin film lubricant of a type having a molecule with marked polar activity such as one with a long carbon chain (e.g., Palmitic or Oleic Acid) terminated by an unsaturated carboxyl group (e.g., CO.sub.2 H), or an unsaturated hydrocarbon distillate. However, the unbalanced and relatively high forces applied by the rollers of the chain against their cross axis call for a grease-type lubricant. Moreover, the shearing contact between the teeth of the driving sprockets and the outside surface of the beads can benefit from the bearing pressure provided by a grease as well as an adsorbed layer of a thin-film lubricant.
A practical, if not efficient, compromise practiced in the prior art consists of lubricating the bicycle chain by dipping it in melted paraffin, wiping the excess lubricant with a rag, then letting the paraffin solidify into a non-tacky film. This approach has some serious limitations, the most obvious being the fact that the chain can only be serviced when off the bicycle. More significant, however, are the facts that paraffin has a poor water tolerance and can disintegrate into flakes when contacted by a small amount of moisture, and, second does not provide a very effective lubricant for the internal and external surface of the rollers and their axles which are subject to both high pressures and shearing forces. Accordingly, there is a need for a multi-functional lubricant specifically formulated for use on bicycle chains and similar mechanisms operating in dusty environments under low speeds, low temperatures, and uneven stresses.